* @param nullAsMax whether to consider null as the maximum value.
* If false, null is considered as the minimum value.
*/
public FieldComparator(String orderBy, boolean ascending, boolean nullAsMax) {
if (Strings.isBlank(orderBy)) {
throw new UiException("Empty fieldnames: "+ orderBy);
}
_fieldnames = parseFieldNames(orderBy, ascending);
_maxnull = nullAsMax;
}